TireFitLab

285/60 R18 vs 33x12.50 R15

285/60 R18 vs 33x12.50 R15

33x12.50 R15 is outside the configured tolerance for 285/60 R18: +4.9% diameter and +4.9% speedometer effect.

Fitment verdict

33x12.50 R15 is outside the configured tolerance for 285/60 R18: +4.9% diameter and +4.9% speedometer effect.

Metric This size: 285/60 R18 Alternative: 33x12.50 R15 Difference Verdict
Overall diameter 31.46 in 33.00 in +4.9% Too tall
Section width 11.22 in 12.50 in +1.28 in Computed difference
Sidewall height 6.73 in 9.00 in +2.27 in Computed difference
Circumference 98.85 in 103.67 in +4.9% Too tall
Speedo 0.0% +4.9% +4.9% Outside tolerance

Compare sizes

Looks valid
Looks valid
Units
✕ Out of toleranceDiameter +4.9% (+1.54 in) · US (~3%)
  • Out of tolerance · Diameter +4.9%.
  • Speedo @ 60: 60 mph → 62.9 mph.
  • Sidewall +2.27 in · Width +1.28 in.
Diameter+4.9%+1.54 in
Speedo @ 60+4.9%60 mph → 62.9 mph
Sidewall+2.27 inWidth +1.28 in
How this result is calculated

Computed from nominal tire-size geometry: diameter, circumference and speedometer error. It does not check wheel-arch, suspension or brake clearance.

Methodology
Diameter
31.46 in 33.00 in+1.54 in
Sidewall
6.73 in 9.00 in+2.27 in
Width
11.22 in 12.50 in+1.28 in
Circumference
98.85 in 103.67 in+4.9%
Revs / mile
641 611
Speedo @ 60
60 mph 62.9 mph+4.9%
Δ⌀ +39.0 mm
  • Current — 285/60 R18
  • New — 33x12.50 R15
  • Grounded to the road: the axle rises +0.77 in.

Result report

285/60 R18 33x12.50 R15 · Out of tolerance

Use this size when shopping: 33x12.50 R15

Use this size when shopping

Geometric estimate. Always verify physical clearance (arches, suspension, brakes) before fitting.

Safe alternative sizes

SizeDiameterSpeedo @ 100Use this
−1″ 245/75R17+0.0%+0.0%
OE 285/60R18+0.0%+0.0%
+1″ 265/60R19+0.2%+0.2%
+2″ 265/55R20+0.0%+0.0%

285/60 R18 · 33x12.50 R15 · Methodology

Last reviewed: 2026-06-28
What changed
  • Reviewed deterministic geometry, load/speed references, sitemap inclusion and localized page shell.